Refrigerator

ABSTRACT

Provided is a refrigerator. The refrigerator is characterized by enabling at least a part of a refrigerator door to be selectively transparent by a user&#39;s operation, such that the user sees through an inside of the refrigerator while the refrigerator door is closed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of prior U.S. patentapplication Ser. No. 16/416,498 filed May 20, 2019, which is acontinuation of U.S. patent application Ser. No. 15/340,056 filed Nov.1, 2016, now U.S. Pat. No. 10,342,363, which claims priority under 35U.S.C. § 119 to Korean Application No. 10-2016-0001298 filed on Jan. 5,2016, whose entire disclosures are hereby incorporated by reference.

BACKGROUND

Generally, a refrigerator is a home appliance which stores food at a lowtemperature in a storage space. The refrigerator is formed to cool aninside of the storage space using cooling air generated through heatexchange with a refrigerant circulated in a refrigeration cycle, andkeeps the stored food in an optimum state.

SUMMARY

The present invention is directed to a refrigerator which enables atleast a part of a refrigerator door to be selectively transparent by anuser's operation, such that the user sees through an inside of therefrigerator while the refrigerator door is closed.

Also, the present invention is directed to a refrigerator in which atleast a part of a front surface of a refrigerator door is formed of halfglass, and a lighting unit in the refrigerator is turned on/off by auser's operation, and thus the user sees through an inside of therefrigerator while the refrigerator door is closed.

Also, the present invention is directed to a refrigerator whichuniformly illuminates an entire opening part when a lighting unit isturned on.

Also, the present invention is directed to a refrigerator which isselectively transparent by a knocking operation on a refrigerator door,and enables an inside of the refrigerator to be visible.

Also, the present invention is directed to a refrigerator which enhancesrecognition performance and reliability of an operation for enabling aninside of the refrigerator to be visible through a panel assembly whilea refrigerator door is closed.

Also, the present invention is directed to a refrigerator which preventsexposure of a detection device detecting an operation for enabling atleast a part of a refrigerator door to be selectively transparent.

Also, the present invention is directed to a refrigerator in which adetection device for detecting a user's operation is easily installedand assembled, and maintenance thereof is easily performed.

Also, the present invention is directed to a refrigerator which is ableto prevent dew condensation on a surface of a refrigerator door formedof a glass material and enabling an inside of the refrigerator to beseen through.

Also, the present invention is directed to a refrigerator which enablesa panel plate formed of a glass material to be firmly installed andfixed to a door, and also enables a step difference or a gap in aninstalled state to be minimized.

Also, the present invention is directed to a refrigerator which enablesan insulation to be completely filled in an inside of a door.

Also, the present invention is directed to a refrigerator which easilyguides an electric wire inside a door, and prevents interference whenthe door is rotated.

Also, the present invention is directed to a refrigerator in which aninternal space of a door basket is able to be utilized variously.

According to an aspect of the present invention, there is provided arefrigerator including a cabinet configured to form a storage space; amain door configured to open and store the storage space, and having anopening part which is in communication with the storage space; asub-door rotatably installed at the main door and configured to open andclose the opening part; a panel assembly provided at the sub-door, andhaving a half-mirror structure which allows to selectively see throughan inside of the opening part; a knock detection device disposed at arear surface of the panel assembly, and configured to detect a user'knocking operation on the panel assembly; and a door lighting unitprovided above the panel assembly, turned on or off by the knockdetection device to selectively illuminate an internal space of theopening part, such that the panel assembly selectively becomestransparent.

The sub-door may include an outer plate which is formed of a metal platematerial, forms an exterior of the sub-door and has a panel installationopening at which the panel assembly is installed; a door liner which isspaced apart from the outer plate, forms a perimeter of a rear surfaceof the sub-door, and forms a space, in which an insulation is filled, atan outside of the panel assembly; an upper cap decoration which iscoupled to upper ends of the outer plate and the door liner, and formsan upper surface of the sub-door; and a lower cap decoration which iscoupled to lower ends of the outer plate and the door liner, and forms alower surface of the sub-door.

A support frame which supports the outer plate and the panel assemblymay be formed at a perimeter of the panel installation opening.

A plate insertion part in which a plate bent part bent along theperimeter of the penal installation opening is accommodated may beformed at the support frame.

A plurality of protrusions may be formed at an inside of the plateinsertion part, and a plate hole in which the plurality of protrusionsare inserted may be formed at the plate bent part.

A plurality of holes through which a foaming solution is introduced maybe formed along the plate insertion part.

The holes may be formed at positions corresponding to the protrusions.

The plate bent part may be in close contact with a side end of the panelassembly.

The support frame may be bonded to the rear surface of the panelassembly.

A heater groove in which a heater disposed along an edge of the panelassembly is accommodated may be formed at the support frame.

An aluminum sheet may be interposed between the support frame and thepanel assembly.

The support frame may include an upper frame which accommodates an upperend of the panel installation opening, side frames which accommodateboth side ends of the panel installation opening; and a lower framewhich accommodates a lower end of the panel installation opening, andthe upper frame, the side frames and the lower frame may be coupled toeach other.

A detection device hole through which a front end of the knock detectiondevice passes may be formed at the lower frame.

An upper hinge installation part to which an upper hinge connecting themain door with the cabinet is shaft-coupled may be formed at an upperend of the main door, and a sub-upper hinge installation part to which asub-upper hinge connecting the sub-door with the cabinet isshaft-coupled may be formed at an upper end of the sub-door, and a hingeshaft of the sub-upper hinge may be formed in a cylindrical shape whichguides an access of an electric wire to an inside of the sub-door.

The hinge shaft of the sub-upper hinge may be formed to have a circularcross section of which one side is opened.

A connector may be provided at an end of the electric wire guided to anoutside of the sub-door through the hinge shaft of the sub-upper hinge,and may be coupled to an electric wire guided toward the cabinet.

The sub-upper hinge installation part may include a sub-hinge coverwhich accommodates the sub-upper hinge and further accommodates theelectric wire coupled to the connector.

A main hinge cover which accommodates the upper hinge may be provided,and a sub-hinge cover which accommodates the sub-upper hinge may beprovided, and the main hinge cover and the sub-hinge cover may have aconnection part which rotatably connects each other, and the electricwire may be guided from the inside of the sub-door to the cabinetthrough the connection part.

The connection part may include a main connection part which is locatedat an upper side of a rotating center of the upper hinge and of which atleast a part of an upper surface is opened; and a sub-connection partwhich is seated on the main connection part and is in communication withthe main connection part, and centers of the upper hinge, the mainconnection part and the sub-connection part may be concentricallylocated.

The sub-hinge cover may be formed in a shape corresponding to a spacebetween the sub-upper hinge installation part and the main hinge cover.

A plurality of door baskets may be installed at the opening part.

A front end of each of the door baskets which face the sub-door may bespaced part from a rear surface of the sub-door.

A front surface of each of the door baskets may be formed to be inclinedfrom one side thereof toward the other side thereof and thus to begradually distant from the rear surface of the sub-door.

The door lighting unit may be disposed at an upper portion of theopening part, and may also be disposed between the front surface of thedoor basket and the rear surface of the sub-door.

The refrigerator may further include a dividing member which isrotatably provided at each of both side surfaces of the door basket,extends so as to cross an inside of the door basket, and is rotated at apreset angle to divide the inside of the door basket.

The refrigerator may further include a stopper which is installed ateach of both side surfaces of the door basket so that the dividingmember is inserted therein, and in which a fixing groove in which thedividing member is inserted is formed at each set angle of acircumference thereof so as to fix the dividing member at the set angle.

The dividing member may include a dividing part which crosses the insideof the door basket, a first bent part which is bent from each of bothends of the dividing part, a second bent part which is bent again fromthe first bent part and inserted into the fixing groove, and aninsertion part which is bent from an end of the second bent part androtatably inserted into a center of the stopper.

The first bent part and the second bent part may form to have differentlengths from each other.

A sensor opening in which the knock detection device is inserted may beformed at a rear surface of the door liner.

The refrigerator may further include an accommodation case which isinstalled at the door liner to be in communication with the sensoropening, extends to the rear surface of the panel assembly, and forms aspace for accommodating the knock detection device.

The knock detection device and a detection device PCB which determines asignal of the knock detection device may be installed at an inside ofthe accommodation case.

An insert cover may be installed at the sensor opening, and thedetection device PCB which determines a signal of the knock detectiondevice may be installed at the insert cover.

An insert cover which shields the sensor opening may be installed at thesensor opening, and the insert cover may include a cover part which isformed in a shape corresponding to the sensor opening, and an insertionpart which extends from the cover part, is inserted into the sub-door,and at which the detection device PCB for determining a signal of theknock detection device is installed.

An insert cover which shields the sensor opening may be installed at thesensor opening, and a cover groove which forms a part of a liner groovein which a sub-gasket is installed may be formed at the insert cover.

The knock detection device may include a microphone module which is incontact with the rear surface of the panel assembly and receives a soundgenerated by vibration due to a knock transmitted through the panelassembly; an elastic member which presses the microphone module towardthe panel assembly; and a support member in which the elastic member isaccommodated and which is installed and fixed to the inside of thesub-door.

The microphone module may include a microphone accommodation part whichis formed of an elastic material to accommodate a microphone, and anopening which faces the panel assembly and a protrusion which protrudesalong a circumference of the opening and is in close contact with thepanel assembly may be formed at the microphone accommodation part.

The panel assembly may include a front panel which forms a front surfaceof the sub-door, and is formed in a half mirror which is selectivelytransparent by reflecting a part of light and transmitting another partof the light; a plurality of insulation panels which are spaced apartfrom the front panel, and formed of transparent tempered glass; and aspacer bar which is provided between the front panel and the insulationpanel and between the insulation panels, and spaces and seals betweenthe front panel and the insulation panel and between the insulationpanels.

The front panel may extend outward further than the insulation panel,and a bezel which blocks the light may be formed along an extending edgeof the front panel, and the knock detection device may be disposed at arear surface of the bezel.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features will beapparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an example refrigerator;

FIG. 2 is a perspective view illustrating a state in which a sub-door ofthe refrigerator is opened;

FIG. 3 is a perspective view illustrating a state in which a main doorof the refrigerator is opened;

FIG. 4 is an exploded perspective view illustrating a coupling structurebetween the main door and the sub-door,

FIG. 5 is a partial perspective view illustrating a hinge couplingstructure between the main door and an upper end of the sub-door;

FIG. 6 is a partial perspective view illustrating a state in which ahinge cover is installed at the main door and the sub-door;

FIG. 7 is a partial perspective view illustrating the hinge couplingstructure of a lower end of the main door;

FIG. 8 is a perspective view of a refrigerator door of the refrigeratorwhen being seen from a rear;

FIG. 9 is a perspective view of an example of a door basket

FIG. 10 is an exploded perspective view of the door basket;

FIG. 11 is a perspective view illustrating a use state of a dividingmember of the door basket;

FIG. 12 is a front view of the sub-door;

FIG. 13 is an exploded perspective view of the sub-door;

FIG. 14 is an exploded perspective view of an example of a door lightingunit;

FIG. 15 is a cross-sectional view taken along line 15-15′ of FIG. 1;

FIG. 16 is a cross-sectional view taken along line 16-16′ of FIG. 12;

FIG. 17 is a perspective view of an example of a support frame FIG. 18is an exploded perspective view illustrating a coupling structure of anupper portion of the support frame;

FIG. 19 is a perspective view of an upper frame forming the supportframe;

FIG. 20 is a perspective view of a side frame forming the support framewhen being from a front;

FIG. 21 is a perspective view of the side frame forming the supportframe when being from a rear;

FIG. 22 is an exploded perspective view illustrating a couplingstructure of a lower portion of the support frame;

FIG. 23 is a perspective view of a lower frame forming the supportframe;

FIG. 24 is a cross-sectional view taken along line 24-24′ of FIG. 12;

FIG. 25 is a cross-sectional view taken along line 25-25′ of FIG. 12;

FIG. 26 is a cross-sectional view taken along line 26-26′ of FIG. 12;

FIG. 27 is a cross-sectional view taken along line 27-27′ of FIG. 12;

FIG. 28 is an exploded perspective view illustrating an example of acoupling structure of a knock detection device when being seeing from afront;

FIG. 29 is an exploded perspective view illustrating the couplingstructure of the knock detection device when being seeing from a rear;

FIG. 30 is an exploded perspective view of the knock detection device;

FIG. 31 is a cross-sectional view illustrating a microphone structure ofthe knock detection device;

FIG. 32 is a cross-sectional view taken along line 32-32′ of FIG. 12;

FIG. 33 is a cross-sectional view taken along line 33-33′ of FIG. 12;

FIG. 34 is a block diagram illustrating a flow of a control signal ofthe refrigerator;

FIG. 35 is a flowchart sequentially illustrating an operation of thesub-door of the refrigerator;

FIG. 36 is a perspective view illustrating a state before an knockingoperation in the refrigerator; and

FIG. 37 is a perspective view illustrating a state after the knockingoperation in the refrigerator.

DETAILED DESCRIPTION

As illustrated in FIG. 1, an external appearance of a refrigerator 1 maybe formed by a cabinet 10 which forms a storage space and a door whichopens and closes the storage space.

An inside of the cabinet 10 may be divided by a barrier 11, and arefrigerator compartment 12 may be formed at an upper portion of thecabinet 10, and a freezer compartment 13 may be formed at a lowerportion of the cabinet 10.

The door may include a refrigerator compartment door 20 and a freezercompartment door 30. The refrigerator compartment door 20 may be formedto open and close an opened front surface of the refrigeratorcompartment 12, and the freezer compartment door 30 may be formed toopen and close an opened front surface of the freezer compartment 13.

One pair of refrigerator compartment doors 20 may be provided left andright, and the refrigerator compartment 12 may be formed to be shieldedby the pair of refrigerator compartment doors 20. The freezercompartment door 30 may be withdrawn in a drawer manner, and thus may beopened and closed by inserting and withdrawing motions.

Various accommodation members such as a shelf, a drawer and a basket maybe provided inside the refrigerator compartment 12 and the freezercompartment 13. The accommodation members may be inserted or withdrawnwhile the refrigerator compartment door 20 and the freezer compartmentdoor 30 are opened, and food may be accommodated and stored in therefrigerator and freezer compartments by the inserting and withdrawingmotions of the accommodation members.

The exterior of the refrigerator 1 may be formed of a metal material t.A dispenser 22 which dispenses water or ice may be provided at therefrigerator compartment door 20.

A right one of the pair of refrigerator compartment doors 20 may beformed to be doubly opened and closed. Specifically, the rightrefrigerator compartment door 20 may include a main door 40 which opensand closes the refrigerator compartment 12, and a sub-door 50 which isrotatably disposed at the main door 40 to open and close an opening part403 formed at the main door 40.

The main door 40 may be formed to have the same size as that of a leftone of the pair of refrigerator compartment doors 20, may be rotatablyinstalled at the cabinet 10 by an upper hinge 401 and a lower hinge 402,and may open and close at least a part of the refrigerator compartment12.

The opening part 403 which is opened in a predetermined size is formedat the main door 40. A door basket 43 is installed at a rear surface ofthe main door 40 including an inside of the opening part 403. A user mayhave access to the door basket 43 through the opening part 403 withoutopening of the main door 40. At this point, a size of the opening part403 may correspond to most of a front surface of the main door 40 excepta part of an edge of the main door 40.

The sub-door 50 is rotatably installed at the front surface of the maindoor 40, and opens and closes the opening part 403. Therefore, access tothe opening part 403 may be allowed by opening the sub-door 50.

A size of the sub-door 50 is formed to be same as that of the main door40 and thus to shield an entire front surface of the main door 40. Themain door 40 and the sub-door 50 may be formed to be coupled to eachother while the sub-door 50 is closed, and to have the same size andshape as those of the left refrigerator compartment door 20. Asub-gasket 591 may be provided at a rear surface of the sub-door 50 toseal between the main door 40 and the sub-door 50.

A panel assembly 54 formed of a transparent material such as glass isprovided at a center of the sub-door 50. Therefore, even while thesub-door 50 is closed, the user may see through an inside of the openingpart 403. The sub-door 50 may be referred to as a see-through door.

The panel assembly 54 may be formed to have a controllable lighttransmittance and reflectivity, and thus may be selectively changed intoa transparent or opaque state according to a user's operation. The panelassembly 54 may be changed into the transparent state only upon a user'srequest to allow the user to see through the refrigerator, otherwise maybe maintained in the opaque state.

A sub-upper hinge 51 and a sub-lower hinge 52 may be provided at anupper end and a lower end of the sub-door 50, respectively, and thesub-door 50 may be rotatably installed at the front surface of the maindoor 40. The sub-door 50 may be formed to be independently rotated whilethe main door 40 is closed, and thus to open and close the opening part403.

A handle 23 may be provided at a front surface of the refrigeratorcompartment door 20. The handle 23 may be formed at each of adjacentends of the pair of refrigerator compartment doors 20. The handle 23 ofthe right refrigerator compartment door 20 may be provided at a frontsurface of the sub-door 50.

An operating button 231 is provided at the handle 23, and a locking unit232 which is operated by the operating button 231 is provided at thesub-door 50. The locking unit 232 protrudes to a rear of the sub-door50, and may be selectively separated from a restricting member 404 ofthe main door 40 by an operation of the operating button 231.

Therefore, while the sub-door 50 is closed, the locking unit 232 ismaintained in a coupled state to the restricting member 404. In thisstate, when the handle 23 is pulled, the main door 40 is rotated, andthus the refrigerator compartment 12 may be opened.

When the user pushes the operating button 231 while the sub-door 50 isclosed, the locking unit 232 is separated from the restricting member404, and only the sub-door 50 may be rotated. The opening part 403 maybe opened by rotation of the sub-door 50.

An accommodation case 41 is formed at the rear surface of the main door40. The accommodation case 41 serves to define an accommodation spacelocated at the rear surface of the main door 40, and a plurality of doorbaskets 43 are disposed therein.

As illustrated in FIGS. 4-6, an upper hinge installation part 405 atwhich the upper hinge 401 is installed is formed at an upper end of themain door 40 to be recessed. The upper hinge 401 is installed and fixedto the cabinet 10, and a hinge shaft 4011 is inserted into a hinge hole4051 of the upper hinge installation part 405, and thus the main door 40is rotatably installed at the cabinet 10.

A sub-upper hinge installation part 501 at which the sub-upper hinge 51is installed is formed at an upper end of the sub-door 50 to berecessed. The sub-upper hinge 51 is installed and fixed to the upperhinge installation part 405, and a hinge shaft 511 is inserted into ahinge hole 5011 of the sub-upper hinge installation part 501, and thesub-door 50 is rotatably installed at the main door 40.

The hinge shaft 511 of the sub-upper hinge 51 may be formed in a tubeshape having a cross section of which one side is opened. Such across-sectional structure provides an internal space of the hinge shaft511 which further expands. Therefore, electric wires L which areconnected with electronic components (a heater, a knock detection deviceand a door lighting unit which will be described below) provided at thesub-door 50 may be guided outside the sub-door 50 through the hingeshaft 511 of the sub-upper hinge 51, and may be connected to a maincontrol part 2 located on the cabinet 10.

The upper hinge 401 and the sub-upper hinge 51 are shielded by a mainhinge cover 45 and a sub-hinge cover 53. The main hinge cover 45 and thesub-hinge cover 53 are connected to each other, and the electric wires Lwhich are guided to an outside through the sub-upper hinge 51 may passthrough the sub-hinge cover 53, and may be guided toward the maincontrol part 2 through an inside of the main hinge cover 45.

Specifically, the main hinge cover 45 is formed so that a lower portionof the hinge is opened, and a recessed space is formed in the hinge toaccommodate the entire upper hinge 401. A separate PCB for controllingthe electronic components provided at a side of the sub-door 50 may beaccommodated inside the main hinge cover 45.

The main hinge cover 45 may have a structure which is matched with oneside of the cabinet 10, or a coupling structure which is installed andfixed by a separate coupling member. A part of the main hinge cover 45is formed to extend toward the upper hinge installation part 405 of themain door 40.

An extension part 451 which extends toward a rotating axis of the upperhinge 401 may be further formed at one side of the main hinge cover 45.A main connection part 452 may be formed at an end of the extension part451. The main connection part 452 may be formed to be stepped downwardfrom the end of the extension part 451. The main connection part 452 maybe formed in a circular shape, and a center of the main connection part452 may be located on an extension line of the hinge shaft 4011 of theupper hinge 401. A connection part hole 453 is opened at an uppersurface of the main connection part 452 so that the electric wires Lpass through the connection part hole.

The sub-hinge cover 53 is formed so that a lower portion thereof isopened, and a recessed space is formed therein to accommodate the entiresub-upper hinge 51. The sub-hinge cover 53 may be installed and fixed tothe upper hinge installation part 405. And a part of the sub-hinge cover53 may extend toward the sub-upper hinge installation part 501, and mayshield the sub-upper hinge 51.

A cover fixing part 531 which is recessed downward is formed at one sideof the sub-upper hinge 51, and a coupling member like a screw may passthrough the cover fixing part 531, may be fastened to the sub-upperhinge installation part 501, and thus may fix the sub-hinge cover 53.

A shape of the sub-hinge cover 53 is formed corresponding to a spacebetween the sub-upper hinge installation part 501 and the main hingecover 45 while the sub-door 50 is closed, and does not interfere withthe sub-door 50 and the main door 40 when the sub-door 50 and the maindoor 40 are opened and closed.

A sub-connection part 532 is formed at one side of the sub-hinge cover53. The sub-connection part 532 is formed to extend toward the main door40, and seated on the upper surface of the main connection part 452. Atthis time, a lower surface of the sub-connection part 532 is opened, andthus an inside of the sub-connection part 532 may be in communicationwith an inside of the main connection part 452. Like the main connectionpart 452, the sub-connection part 532 is formed to have a circular crosssection, and located on an extension line of a center of the rotatingaxis of the upper hinge 401.

That is, the center of the rotating axis of the upper hinge 401 andcenters of the main connection part 452 and the sub-connection part 532are concentrically disposed. Therefore, while the main door 40 and thesub-door 50 are rotated, the rotating axis of the upper hinge 401, themain connection part 452 and the sub-connection part 532 may be stablyrotated without being shaken. When the main door 40 or the sub-door 50is rotated, the electric wires L guided through the sub-hinge cover 53may pass, in turn, through the sub-connection part 532 and the mainconnection part 452, and may be guided inside the main hinge cover 45.

The electric wires L may be connected by connectors 502 and 406, and theconnectors 502 and 406 may be located inside the sub-hinge cover 53.Therefore, after the sub-connector 502 which is connected to ends of theelectric wires L exposed outward through a rotating axis of thesub-upper hinge 51 and the main connector 406 of the electric wires Lwhich are connected to the main control part 2 and guided toward thesub-upper hinge installation part 501 through the main hinge cover 45are connected to each other, the sub-hinge cover 53 may be coveredthereon, and thus the electric wires L, the connectors 502 and 406 andthe sub-upper hinge 51 may be shielded.

The lower hinge 402 which supports a lower end of the main door 40 isinstalled at one side of a front surface of the cabinet 10. Thesub-lower hinge 52 which supports the sub-door 50 is installed at thelower end of the main door 40.

As illustrated in FIG. 7, the lower hinge 402 is installed at the frontsurface of the cabinet 10, and serves to enable the main door 40 to berotatably supported.

The lower hinge 402 may include a main fixing part 4021 which is fixedto the front surface of the cabinet 10, a main support part 4022 whichis vertically bent from the main fixing part 4021 and supports the lowerend of the main door 40, and a hinge shaft 4023 which extends upwardfrom the main support part 4022 and is inserted into the main door 40.The lower end of the main door 40 is supported by the lower hinge 402,and the main door 40 may be rotated about the hinge shaft 4023.

The sub-lower hinge 52 is located at a front of the lower hinge 402, andprovided at the lower end of the main door 40. The sub-lower hinge 52may be installed at a sub-lower hinge installation part 407 which isrecessed from the lower end of the front surface of the main door 40.

The sub-lower hinge 52 may include a sub-fixing part 521 which is fixedto the sub-lower hinge installation part 407, and a sub-support part 522which is bent from a lower end of the sub-fixing part 521 and extendsforward, and a hinge shaft 523 which extends upward from the sub-supportpart 522 and is inserted into the sub-door 50. Therefore, the lower endof the sub-door 50 is supported by the sub-lower hinge 52, and thesub-door 50 may be rotated about the hinge shaft 523.

FIG. 8 is a perspective view of the refrigerator door of therefrigerator when being seen from a rear.

As illustrated in FIG. 8, a front surface of the accommodation case 41is opened, and the opened front surface of the accommodation case 41 maybe formed corresponding to the size of the opening part 403. Therefore,when the sub-door 50 is opened, the opening part 403 is exposed, and theaccess to the door basket 43 inside the accommodation case 41 throughthe opening part 403 may be allowed.

A case door 42 which is opened and closed by rotation may be provided ata rear surface of the accommodation case 41. While the main door 40 isopened, the access to the door basket 43 may be allowed by opening thecase door 42.

A case opening 410 and a door opening 421 which allows the cooling airin the refrigerator to be introduced into the accommodation case 41 maybe formed at the accommodation case 41 and the case door 42. Atemperature inside the accommodation case 41 may be maintained to be thesame as an internal temperature of the refrigerator compartment 12.

A molded end at which the door basket 43 is installed may be formed atthe rear surface of the main door 40, more specifically, both sidesurfaces of the opening part 403. The molded end may be formed in anuneven structure, and may also be formed to enable the door basket 43 tobe separated.

As illustrated in FIGS. 9 and 10, the door basket 43 is formed so thatan upper surface of the door basket is opened, and has an installationpart 431 which is disposed inside the opening part 403. The installationpart 431 has a width corresponding to that of the opening part 403, andan installation groove 4311 which is coupled to the molded end of theopening part 403 may be formed at both side surfaces thereof.

A rear surface of the installation part 431 which faces the rear surfaceof the sub-door 50 may be formed to be inclined. Therefore, apredetermined distance may be formed between the rear surface of thesub-door 50 and a rear surface of the installation part 431, and lightemitted from a door lighting unit 49 is not blocked, and the lightilluminates the entire opening part 403.

The door basket 43 may include a dividing member 432, a stopper 433which enables the dividing member 432 to be fixed at a set angle, and astopper cap 434 for installation of the stopper 433.

The dividing member 432 may be formed of a wire or rod material, and mayhave a circular cross section having a predetermined diameter. Thedividing member 432 may include a dividing part 4321 which extends tocross the installation part 431, a first bent part 4322 which is bentvertically from each of both ends of the dividing part 4321, a secondbent part 4323 which is bent vertically from the first bent part 4322,and an insertion part 4324 which is bent outward from each of both endsof the second bent part 4323 and inserted into the stopper 433.

The stopper 433 is installed at an inner side surface of theinstallation part 431, and disposed at each of left and right sidesurfaces to fix the dividing member 432. The stopper 433 may be formedin a cylindrical shape, and a cap insertion hole 4331 in which thestopper cap 434 is installed may be formed at one side surface thereofwhich is contact with the installation part 431. A stopper hook 4332which fixes the stopper 433 to the installation part 431 may be formedat an outside of the cap insertion hole 4331.

A center hole 4333 in which the insertion part 4324 of the dividingmember 432 is inserted may be formed at a center of opposite surfaces ofthe stopper 433 which are disposed at both sides of the stopper 433. Afixing groove which is recessed inward centering on the center hole 4333may be formed at a circumference of the stopper 433. The fixing grooveis formed in a shape corresponding to that of an outer surface of thedividing member 432, and accommodates and fixes the second bent part4323 of the dividing member 432.

The fixing groove may include a first fixing groove 4334 which enablesthe dividing member 432 to be located at a first position, a secondfixing groove 4335 which enables the dividing member 432 to be locatedat a second position, and a third fixing groove 4336 which enables thedividing member 432 to be located at a third position. The first fixinggroove 4334 and the third fixing groove 4336 may be formed at positionswhich vertically face each other in upward and downward directions ofthe stopper 433, and the second fixing groove 4335 may be formed at amiddle portion between the first fixing groove 4334 and the third fixinggroove 4336. Each of the fixing grooves may be disposed at an angularinterval of 90°, and may fix the dividing member 432 at each positionwhich is rotated by an angle of 90°.

The first position corresponds to a state in which the second bent part4323 is inserted into the first fixing groove 4334. In this state, thedividing part 4321 of the dividing member 432 is in close contact withan inner wall surface of the door basket 43, as illustrated in FIG. 9,and an entire internal space of the door basket 43 may be used as oneaccommodation space.

The second position corresponds to a state in which the second bent part4323 is inserted into the second fixing groove 4335. In this state, thedividing part 4321 of the dividing member 432 is located at a positionwhich is spaced apart from the inner wall surface of the door basket 43,and thus the internal space of the door basket 43 is divided into twospaces. At this time, the position of the dividing part 4321 is locatedat a position which is spaced apart from a position of the stopper 433by a length of the second bent part 4323, and divides the space.

The third position corresponds to a state in which the second bent part4323 is inserted into the third fixing groove 4336. In this state, likethe second position, the dividing part 4321 of the dividing member 432is located at a position which is spaced apart from the inner wallsurface of the door basket 43, and the internal space of the door basket43 is divided into two spaces.

At this time, the position of the dividing part 4321 is located at aposition which is spaced apart from the position of the stopper 433 by alength of the first bent part 4322, and divides the space. Since thefirst bent part 4322 and the second bent part 4323 are formed to havedifferent lengths from each other, the user may selectively use thespace according to a divided degree of the space occurring by a lengthdifference between the first bent part 4322 and the second bent part4323.

In particular, as illustrated in FIG. 11, in the case in which thedividing member 432 is located at the second position and the thirdposition, and thus divides the internal space of the door basket 43 intothe two spaces, each of the spaces has a narrow width and a high height,and thus may effectively store sauce bottles or tube containers whicheasily fall down.

A stopper fixing hole 435 is formed at both side surfaces of theinstallation part 431. A fixing groove 4351 is further formed at thestopper fixing hole 435 so that the stopper hook 4332 is hooked andrestricted thereto. Therefore, the stopper 433 may be fixed to the innerside surface of the installation part 431 so as not to be rotated. Thestopper cap 434 may be provided outside the installation part 431. Thestopper cap 434 is installed in the stopper fixing hole 435, and a caphook 4341 provided at a center of the stopper cap 434 may pass throughthe stopper fixing hole 435, and may be hooked and restricted into thecap insertion hole 4331. Therefore, the stopper 433 may be furtherfirmly fixed by the stopper cap 434.

As illustrated in FIGS. 12 and 13, the sub-door 50 may include an outerplate 55 which forms an exterior of the sub-door 50, the panel assembly54 which is installed at an opening of the outer plate 55, a door liner58 which is installed to be spaced apart from the outer plate 55, and anupper cap decoration 56 and a lower cap decoration 57 which form anupper surface and a lower surface of the sub-door 50.

The outer plate 55 forms the exterior of the front surface and a part ofa perimeter surface of the sub-door 50, and may be formed of a stainlessmaterial. A panel installation opening 551 in which the panel assembly54 is formed is formed at a center of the outer plate 55. The panelinstallation opening 551 is a space which sees through the inside of theopening part 403 of the main door 40, and may be formed to be the sameas or similar to the size of the opening part 403. A plate bent part 552which is vertically bent inward along a perimeter of the panelinstallation opening 551 is formed. The plate bent part 552 is bent soas to be inserted into a support frame 60, and plate holes 5521 whichare opened at regular intervals may be continuously formed at the platebent part 552.

The panel assembly 54 is formed to shield the panel installation opening551, and while the panel assembly 54 is installed, a front surface ofthe panel assembly 54 may form the same plane as a front surface of theouter plate 55. The panel assembly 54 may be selectively transparentaccording to On/Off of the door lighting unit 49, and may be formed toenable the user to selectively see through the inside of the openingpart 403. The upper cap decoration 56 forms the upper surface of thesub-door 50, and is coupled to upper ends of the outer plate 55 and thedoor liner 58. The sub-upper hinge installation part 501 is formed atone end of the upper cap decoration 56, and an upper boss 5012 in whichthe hinge shaft 523 of the upper hinge 401 is inserted may be installedat the sub-upper hinge installation part 501.

The lower cap decoration 57 forms the lower surface of the sub-door 50,and is coupled to lower ends of the outer plate 55 and the door liner58. A hinge plate 571 is installed at a position of the lower capdecoration 57 at which the sub-lower hinge 52 is installed, and a lowerboss 572 in which the hinge shaft 523 of the sub-lower hinge 52 isinserted may be installed at the hinge plate 571.

Two foaming solution injecting holes 573 may be formed at the lower capdecoration 57. The foaming solution injecting holes 573 are formed toinject a foaming solution which forms an insulation at a perimeter ofthe panel assembly 54 in an internal space of the sub-door 50. At thispoint, to smoothly inject the foaming solution into the sub-door 50, avertical lower side corresponding to a space between an outside of thepanel assembly 54 and an inner side surface of the sub-door 50 is formedto be opened. When the foaming solution is injected, the foamingsolution may be prevented from flowing back or being incompletelyfilled, and may be effectively injected. The foaming solution injectingholes 573 may be shielded by injecting hole caps 574 which are installedat the lower cap decoration 57.

The door liner 58 forms the rear surface of the sub-door 50, and a lineropening 581 is formed at an area at which the panel assembly 54 isdisposed. A liner groove 582 which maintains a shape of the door liner58 may be formed along the liner opening 581 at a perimeter of the doorliner 58. The liner groove 582 is recessed from the rear surface of thesub-door 50, and the sub-gasket 591 which seals between the sub-door 50and the main door 40 may be installed thereat.

The locking unit 232 may be installed at one side of the door liner 58,and a knock detection device 82 and a door opening assist device 588which are described below in detail may be installed.

A heater 59 may be provided inside the sub-door 50. The heater 59 isdisposed along a perimeter of a rear surface of the panel assembly 54.Specifically, the heater 59 may be disposed at a rear surface of a frontpanel 541 which forms the front surface of the panel assembly 54, andmay be installed at an area of a bezel 5411, which is formed at aperimeter of the front panel 541, so as not to be exposed outside.

The support frame 60 which fixes the outer plate 55 and the panelassembly 54 along the perimeter of the panel installation opening 551 isprovided at a rear surface of the outer plate 55. The support frame 60may be formed by coupling an upper frame 61, a lower frame 63 and onepair of side frames 62, may also be formed along an edge of the panelinstallation opening 551 to accommodate the plate bent part 552, and maybe in contact with the rear surface of the panel assembly 54. Thesupport frame 60 may fix the heater 59 which is disposed at the rearsurface of the panel assembly 54. The door lighting unit 49 may beinstalled at an upper end of the liner opening 581. The door lightingunit 49 may illuminate a portion at the plurality of door baskets 43disposed at the main door 40 are arranged, may enable the inside of therefrigerator to be brighter than an outside thereof, and thus may enablethe panel assembly 54 to look transparent.

The door lighting unit 49 may include a lamp case 491 which is installedat the door liner 58, a lamp PCB 492 which is accommodated in the lampcase 491 and at which a plurality of LEDs 4921 are disposed, and a lampcover 493 which shields an opened lower surface of the lamp case 491 andis exposed through the opening.

As illustrated in FIGS. 14, 15 and 16 the door lighting unit 49 may beinstalled at a lighting unit installation part 583 which is formed at anupper end of the liner opening 581 of the door liner 58.

A case fixing part 5831 is formed at both ends of the lighting unitinstallation part 583, and a case rib 4911 which protrudes from bothends of the lamp case 491 is hooked and restricted to the case fixingpart 5831, and thus the door lighting unit 49 may be installed andfixed.

The lamp cover 493 is formed to extend long along the door liner 58, andincludes a recessed part 4912 which is formed in the lamp cover to havea recessed space for accommodating the lamp PCB 492. Specifically, asurface of the recessed part 4912 which faces the lamp PCB 492 may beformed to be rounded, and light emitted from the lamp PCB 492 isreflected by a round surface 4913 having a predetermined curvature, anddirected to the lamp case 491. A film which increases reflectivity ofthe light may be attached or coated on an inner surface of the recessedpart 4912, in particular, the round surface 4913.

A lamp PCB installation part 4914 at which the lamp PCB 492 is installedis formed at one surface which faces the round surface 4913. The lampPCB installation part 4914 is formed so that the lamp PCB 492 isinstalled and fixed in a direction crossing the lamp cover 493 at aninside of the lamp case.

An electric wire entrance hole 4915 through which access of the electricwires L connected to the lamp PCB 492 is allowed may be formed at oneside of the lamp PCB installation part 4914. The electric wire entrancehole 4915 may be guided to the internal space of the sub-door 50, andmay pass through the hinge shaft 511 of the sub-upper hinge 52.

The lamp cover 493 is formed so that the light reflected by the roundsurface 4913 of the recessed part 4912 is transmitted through the lampcover, and also formed to shield an opening of the recessed part 4912.The lamp cover 493 is formed to be transparent or semitransparent, suchthat the light reflected by the round surface 4913 and uniformly spreadis transmitted. The light passing through the lamp cover 493 illuminatesthe inside of the refrigerator in an indirect lighting method, and has asurface emitting effect.

The film may be attached to or coated on the lamp cover 493 to moreeffectively diffuse the light. When the lamp cover 493 isinjection-molded, particles or a material which diffuses the light maybe added.

The lighting unit installation part 583 at which the door lighting unit49 is installed extends toward the inside of the opening part 403, andthe lamp cover 493 radiates downward the light from an upper end of theopening part 403 when the door lighting unit 49 is installed.

Rear ends of the plurality of door baskets 43 installed at the openingpart 403 are spaced apart from the rear surface of the sub-door 50, andlocated at the inside of the refrigerator further than the door lightingunit 49. As illustrated in FIG. 15, the light emitted downward from thedoor lighting unit 49 is prevented from being blocked by the doorbaskets 43 or the food accommodated in the door baskets 43.

A front surface of each of the door baskets 43 close to a rear end ofthe panel assembly 54 is formed to be inclined, and the light emitteddownward from the door lighting unit 49 may be prevented from beinginterfered, and may also illuminate the entire opening part 403.

The door lighting unit 49 may be selectively turned on/off according toa user's operation. When the door lighting unit 49 is turned on, theaccommodation space formed at the main door 40 is illuminated. When thedoor lighting unit 49 is turned on, and the accommodation space of themain door 40, i.e., the inside of the refrigerator becomes brighter thanthe outside, the light emitted from the door lighting unit 49 penetratesthe sub-door 50. The user may recognize the transparent sub-door 50, andmay see the accommodation space inside the main door 40 through thesub-door 50 from the outside.

The panel assembly 54 may be installed and fixed to the sub-door 50 bythe support frame 60. One side of the support frame 60 may be fixed tothe outer plate 55, and the other side of the support frame 60 may bebonded to the panel assembly 54 so that the panel assembly 54 is fixedto the panel installation opening 551.

The panel assembly 54 may include the front panel 541, at least one ormore insulation panels 542 disposed at a rear of the front panel 541,and a spacer bar 543 which supports the front panel 541 and theinsulation panel 542 and also supports between a plurality of insulationpanels 542.

The front panel 541 may be formed of a glass material which isselectively see through according to the light transmittance andreflectivity, and may be referred to as a half mirror.

That is, in a state in which the door lighting unit 49 is turned on, thelight inside the refrigerator penetrates the front panel 541, and thefront panel 541 looks transparent. Therefore, the space inside therefrigerator located at a rear of the sub-door 50 or the accommodationspace formed at the main door 40 may be seen from the outside while thesub-door 50 is closed.

When the door lighting unit 49 is turned off, the light does notpenetrate the front panel 541, but is reflected, and the front panel 541serves as a mirror surface. In this state, the space inside therefrigerator located at the rear of the sub-door 50 or the accommodationspace formed at the main door 40 may not be seen from the outside.

The front panel 541 may be surface-treated in various methods so that ahalf mirror effect is provided at the front panel 541. For example, atitan compound may be vacuum-deposited on a front surface of a glasslayer forming the front panel 541.

A silk-screen printing may be performed on a rear surface of the glasslayer forming the front panel 541 using a titan compound (TiO₂)-basedprinting ink which includes a resin for adjusting viscosity, an organicsolvent and an additive, and thus a ceramic printed layer may be formed.

In some examples, a hard coating layer configured with triple layers ofiron, cobalt and chrome may be formed on the rear surface of the glasslayer forming the front panel 541 using an atmospheric pressure chemicalvapor deposition (APCAVD) method or a spraying method in which a liquidcoating material is sprayed.

When the ceramic printed layer or the hard coating layer is formed onthe rear surface of the glass layer, the front panel 541 may be formedto have a light transmittance of 20% to 30% from the outside. When thetransmittance is 20% or less, it is not easy to see through the insidefrom the outside even when the door lighting unit 49 is turned on, andwhen the transmittance is 30% or more, the front surface of the panelassembly 54 does not look like the mirror surface, and a part of theinside of the refrigerator may be seen through.

The bezel 5411 which is formed along the perimeter of the rear surfaceof the front panel 541 may be formed so that the light is nottransmitted through it, and an edge of the front panel 541 at which thebezel 5411 is provided is formed to extend outward further than theinsulation panel 542. Therefore, at the rear surface of the front panel541 at which the bezel 5411 is formed, the support frame 60, the heater59 and the spacer bar 543 are provided so as not to be exposed forwardthrough the front panel 541.

The knock detection device 82 may be disposed at the bezel 5411 which isformed at a lower end of the front panel 541. Therefore, the knockdetection device 82 may also be covered by the bezel 5411 so as not tobe exposed to the outside.

Specifically, the support frame 60 is disposed at an area of the bezel5411 to fix the panel assembly 54. The heater 59 fixed by the supportframe 60 may also be located at the area of the bezel 5411. Therefore,all of the heater 59 and the support frame 60 which are disposed alongan edge of the panel assembly 54 are covered by the bezel 5411 and thusnot exposed to the outside.

The spacer bar 543 is formed at the perimeter of the rear surface of thefront panel 541. The spacer bar 543 serves to enable the front panel 541and the insulation panel 542 to be spaced apart from each other, andalso to seal the space between the front panel 541 and the insulationpart 542.

The spacer bar 543 may also be disposed between the plurality ofinsulation panels 542. The front panel 541, the insulation panel 542 andthe plurality of spacer bars 543 may be bonded to each other by anadhesive, and a sealant may be coated to seal an outer surface of thepanel assembly 54 and among the front panel 541, the insulation panel542 and the spacer bar 543.

The insulation panel 542 may be formed to have a size smaller than thatof the front panel 541, and may be located within an internal area ofthe front panel 541. The insulation panel 542 may be chemicalstrengthening glass in which glass is soaked in an electrolyte solutionat a glass transition temperature or more, and chemically strengthened.

A low-radiation coating layer for reducing heat transfer into thestorage compartment due to radiation may be formed at a rear surface ofthe insulation panel 542. Glass on which the low-radiation coating layeris formed is referred to as low-c glass. The low-radiation coating layermay be formed by sputtering silver or the like on a surface of theglass.

A sealed space between the front panel 541 and the insulation panel 542and a sealed space between the plurality of insulation panels 542 whichare formed by the spacer bar 543 may create a vacuum state so as to beinsulated.

In some examples, an inert gas for the insulation, such as argon, may befilled in the sealed space between the front panel 541 and theinsulation panel 542 and the sealed space between the plurality ofinsulation panels 542. Insulation performance may be ensured by forminga predetermined space between the front panel 541 and the insulationpanel 542 and between the plurality of insulation panels 542 in whichthe inert gas is filled since inert gases have a better insulationproperty than air.

The insulation panel 542 may be formed in a single panel, and may beinstalled to be spaced apart from the front panel 541. Two or moreinsulation panels 542 may be provided to be spaced apart from eachother.

As illustrated in in FIG. 17, the support frame 60 may be formed so thatthe upper frame 61 and the lower frame 63 are disposed up and down, andthe pair of side frames 62 connect between the upper frame 61 and thelower frame 63, and thus may be formed to have a quadrangular shape.

The support frame 60 may be injection molded with a plastic material.The support frame 60 may be formed so that the plate bent part 552 ofthe outer plate 55 is inserted into the support frame 60 while thesupport frame 60 is assembled, and may also be formed so that the heater59 is fixed to the frame 60.

Specifically, plate insertion parts 611, 621 and 631 in which the platebent part 552 is inserted may be formed at the assembled support frame60. The plate insertion parts 611, 621 and 631 may be formed along anentire perimeter of the support frame 60. A plurality of restrictingprotrusions 612, 622 and 632 may be formed at the plate insertion parts611, 621 and 631 to be spaced apart from each other at regularintervals. A plurality of holes 614, 624 and 634 corresponding to therestricting protrusions 612, 622 and 632 may be formed at the plateinsertion parts 611, 621 and 631 so that the foaming solution is easilyintroduced into the plate insertion parts 611, 621 and 631. Therestricting protrusions 612, 622 and 632 may be formed at positionscorresponding to the plurality of holes 614, 624 and 634, and thus therestricting protrusions 612, 622 and 632 may be easily molded during aninjection molding.

Heater grooves 613, 623 and 633 may be formed at the support frame 60 tocorrespond to an arrangement of the heater 59, and the heater 59 may beinstalled.

An entire width of the support frame 60 is formed to be covered by thebezel 5411 provided at the panel assembly 54, and may be formed toextend to an outer end of the insulation panel 542.

As illustrated in FIGS. 18 and 19, the upper frame 61 forms an upperportion of the support frame 60. Both ends of the upper frame 61 arebent downward, and may be coupled to upper ends of the side frames 62.To this end, both ends of the upper frame 61 may be bent downward, andthen may be opened. An upper hook groove 615 in which a side hook 625formed at the upper end of the side frame 62 is inserted may be formedat each of both ends of the upper frame 61.

An upper insertion part 611 may be formed to be recessed from onesurface of the upper frame 61 which is in contact with the rear surfaceof the outer plate 55. The upper insertion part 611 is formed so that aportion of the plate bent part 552 which forms an upper end of the panelinstallation opening 551 is inserted therein.

The upper insertion part 611 may be formed to have a thickness greaterthan that of the outer plate 55 and a protruding height of an upperrestricting protrusion 612 formed at the upper insertion part 611.Therefore, the plate bent part 552 may be inserted into the upperinsertion part 611, and then the upper restricting protrusion 612 may beinserted into the plate hole 5521, and thus the outer plate 55 and theupper frame 61 may be coupled to each other.

An upper heater groove 613 may be formed at an inner side further thanthe upper insertion part 611, i.e., at an opening side of the supportframe 60, and thus may accommodate an upper portion of the heater 59which is disposed along the edge of the front panel 541. An electricwire entrance part 616 is formed at one side of the upper heater groove613, and thus the electric wire L connected to the heater 59 may entertherethrough.

An upper hole 614 may be further formed at the upper insertion part 611corresponding to the upper restricting protrusion 612, and the foamingsolution for forming the insulation may be injected through the upperhole 614, and may be filled inside the upper insertion part 611 of theupper frame 61.

As illustrated in FIGS. 20 and 21, the side frames 62 form both sidesurfaces of the support frame 60. Each of the side frames 62 is formedto have a length which connects between the upper frame 61 and the lowerframe 63. To this end, the side hook 625 is formed at an upper end and alower end of each of the side frames 62. The side hook 625 may becoupled to the upper hook groove 615 of the upper frame 61 and a lowerhook groove 635 of the lower frame 63.

Side ribs 626 which are inserted into the upper insertion part 611 ofthe upper frame 61 and a lower insertion part 631 of the lower frame 63may be formed at the upper end and the lower end of each of the sideframes 62, respectively. Therefore, the side frames 62, the upper frame61 and the lower frame 63 may be maintained in a stably coupled state toeach other.

A side insertion part 621 may be formed to be recessed from one surfaceof each of the side frames 62 in contact with the rear surface of theouter plate 55. The side insertion part 621 may be formed to be insertedinto a portion of the plate bent part 552 which forms both side ends ofthe panel installation opening 551.

At this time, the side insertion part 621 may be formed to have athickness greater than that of the outer plate 55 and a protrudingheight of a side restricting protrusion 622 formed at the side insertionpart 621. Therefore, the plate bent part 552 may be inserted into theside insertion part 621, and then the side restricting protrusion 622may be inserted into the plate hole 5521, and the outer plate 55 and theside frames 62 may be coupled to each other.

A side heater groove 623 may be formed at an inner side further than theside insertion part 621, and may accommodate a side portion of theheater 59 which is disposed along the edge of the front panel 541.

Meanwhile, a side hole 624 may be further formed at the side insertionpart 621 corresponding to the side restricting protrusion 622, and thefoaming solution may be injected through the side hole 624, and may befully filled inside the side insertion part 621 of each of the sideframes 62.

As illustrated in FIGS. 22 and 23, the lower frame 63 forms a lowerportion of the support frame 60. Both ends of the lower frame 63 arebent upward, and may be coupled to lower ends of the side frames 62. Tothis end, both ends of the lower frame 63 may be bent upward, and thenmay be opened. The lower hook groove 635 in which the side hook 625formed at the lower end of the side frame 62 is inserted may be formedat each of both ends of the lower frame 63.

The lower insertion part 631 may be formed to be recessed from onesurface of the lower frame 63 which is in contact with the rear surfaceof the outer plate 55. The lower insertion part 631 is formed so that aportion of the plate bent part 552 which forms a lower end of the panelinstallation opening 551 is inserted into the lower insertion part 631.

The lower insertion part 631 may be formed to have a thickness greaterthan that of the outer plate 55 and a protruding height of a lowerrestricting protrusion 632 formed at the lower insertion part 631.Therefore, the plate bent part 552 may be inserted into the lowerinsertion part 631, and then the lower restricting protrusion 632 may beinserted into the plate hole 5521, and thus the outer plate 55 and thelower frame 63 may be coupled to each other.

A lower heater groove 633 may be formed at an inner side further thanthe lower insertion part 631, and may accommodate a lower end of theheater 59 which is disposed along the edge of the front panel 541.

Meanwhile, a lower hole 634 may be further formed at the lower insertionpart 631 corresponding to the lower restricting protrusion 632, and thefoaming solution may be injected through the lower hole 634, and thusmay be fully filled inside the lower insertion part 631 of the lowerframe 63, and the insulation may be formed.

A detection device hole 636 through which the knock detection device 82which will be described below in detail is exposed is formed at one sideof the lower frame 63. Therefore, the knock detection device 82 may beprovided at a rear of the lower frame 63, and may be in close contactwith the rear surface of the front panel 541 through the detectiondevice hole 636.

Referring to FIGS. 24-27, all of the upper frame 61, the side frames 62and the lower frame 63 are attached to a protruding edge of the frontpanel 541. The upper frame 61, the side frames 62 and the lower frame 63may be bonded to the rear surface of the front panel 541, at which thebezel 5411 is formed, by an adhesive sheet 5412 or an adhesive.

Ends of the upper frame 61, the side frames 62 and the lower frame 63may extend to an outer end of the insulation panel 542. The upper heatergroove 613, the side heater groove 623 and the lower heater groove 633are formed at the ends of the upper frame 61, the side frames 62 and thelower frame 63, and thus the edge of the front panel 541 of which atemperature of the rear surface thereof is relatively lower than that ofthe front surface thereof may be heated. And an aluminum sheet 5413having a predetermined width may be disposed between the heater 59 andthe front panel 541. Therefore, when the heater 59 generates heat, anarea at which the bezel 5411 of the front panel 541 is formed may beequally heated.

The plate bent part 552 of the outer plate 55 is inserted into the upperinsertion part 611, the side insertion part 621 and the lower insertionpart 631 of the upper frame 61, the side frame 62 and the lower frame 63which are attached to the front panel 541.

As illustrated in FIG. 24, the plate bent part 552 is in close contactwith the front panel 541 while being inserted into the side insertionpart 621. The plate hole 5521 of the plate bent part 552 is hooked andrestricted to the side restricting protrusion 622, and thus the outerplate 55 and the side frames 62 may be coupled and fixed to each other.

The foaming solution may be introduced into the side insertion part 621through the side hole 624, and the introduced foaming solution mayenable the plate bent part 552 to be in close contact with the frontpanel 541.

Due to such a structure, the plate bent part 552 formed at the outerplate 55 may be in close contact with an outer end of the front panel541. Therefore, when seen from a front, a gap between an end of theouter plate 55 forming the panel installation opening 551 and the outerend of the front panel 541 may be minimized.

As illustrated in FIGS. 28 and 29, a sensor opening 584 in which theknock detection device 82 is inserted is formed at a lower portion ofthe door liner 58. The sensor opening 584 is formed so that the knockdetection device 82 is inserted from an outside. A detection device PCB83 for processing a knock detecting signal of the knock detection device82 may be formed to have a shape corresponding to an insert cover 585which will be installed, and may be shielded by the insert cover 585.

In a state in which the insert cover 585 is installed, an outer surfaceof the insert cover 585 has the same shape as that of an outer surfaceof the door liner 58. Therefore, the insert cover 585 is installed at aposition through which the liner groove 582 formed at the door liner 58passes, and a cover groove 5854 which is connected with the liner groove582 is formed at the insert cover 585. Therefore, the sub-gasket 591 maybe installed to pass through the liner groove 582 and the cover groove5854.

A detection device accommodating part 586 may be formed along aperimeter of the sensor opening 584. The detection device accommodatingpart 586 forms a part of a space which accommodates the knock detectiondevice 82, is formed to extend toward the outer plate 55, and coupled toan accommodating part case 587 so as to form a space for accommodatingthe knock detection device 82.

The accommodating part case 587 is coupled to a front end of thedetection device accommodating part 586, and forms a remaining space foraccommodating the knock detection device 82. A case coupling part 5871to which a screw is fastened is formed at both ends of the accommodatingpart case 587, and thus the accommodating part case 587 may be coupledand fixed to the detection device accommodating part 586.

A detection device inserting part 5872 in which a front end of the knockdetection device 82 is inserted is formed at the accommodating part case587. An insertion part hole 5873 is formed at a front surface of thedetection device inserting part 5872, and the detection device insertingpart 5872 is inserted into the detection device hole 636. Therefore, afront surface of the knock detection device 82 which is inserted intothe detection device inserting part 5872 may pass through the insertionpart hole 5873 and the detection device hole 636, and may be in closecontact with the rear surface of the front panel 541.

An end of the detection device accommodating part 586 and an end of theaccommodating part case 587 which are in contact with each other may beformed to have slopes corresponding to each other, and thus may becoupled to each other with orientation. Due to coupling between thedetection device accommodating part 586 and the accommodating part case587, a space in which the knock detection device 82 and the detectiondevice PCB 83 are installed is formed inside the sub-door 50.

While the detection device accommodating part 586 and the accommodatingpart case 587 are coupled to each other, the detection deviceaccommodating part 586 and the accommodating part case 587 form a spaceindependent from the space inside the sub-door 50 in which the foamingsolution is injected. Therefore, the user may insert and install theknock detection device 82 through the sensor opening 584 after a foamingprocess is performed at the sub-door 50.

Meanwhile, the insert cover 585 may include a cover part 5851 whichshields the sensor opening 584, and a PCB insertion part 5852 in whichthe detection device PCB 83 is installed. The cover part 5851 is formedto have a shape corresponding to the sensor opening 584 and to shieldthe sensor opening 584, and forms a part of an exterior of the doorliner 58. And a screw hole 5853 may be formed at one side of the coverpart 5851, and the cover part 5851 may be fixed to the door liner 58 bya screw.

The PCB insertion part 5852 is formed to extend from the cover part5851, and also formed to be inserted into the detection deviceaccommodating part 586 when the insert cover 585 is inserted. The coverpart 5851 may be formed corresponding to a size of the detection devicePCB 83 so that the insert cover 585 is inserted and installed into thesensor opening 584 while the detection device PCB 83 is installed. Theelectric wire L which is connected to the knock detection device 82 maybe connected to the adjacent detection device PCB 83. Since thedetection device PCB 83 may be disposed at a lateral side of the knockdetection device 82, the detection device PCB 83 may be connected to theknock detection device 82 in a short distance.

In the case in which the detection device PCB 83 for processing thesignal is located at a distance, there may be a problem that noisegenerated when the signal to be processed is transferred through asignal line may be increased. However, since the detection device PCB 83is located at a position at which the knock detection device 82 isinstalled, the main control part 2 receives only a valid knock-onsignal. Accordingly, the noise due to the signal line between the maincontrol part 2 and the detection device PCB 83 may be minimized. Thatis, the main control part 2 may receive the signal of which the noise isminimized through the detection device PCB 83. Therefore, it is possibleto ensure an accurate recognition rate.

In particular, in the case of the knock detection device 82, a signaloutput through a microphone 8211 is indicated by mV unit, but the maincontrol part 2 which controls an entire operation of the refrigeratorgenerally receives a signal which is basically indicated by V unit.Therefore, due to a scale difference in a physical signal, it is notpreferable that the main control part 2 determines whether the knock-onsignal is normal.

The refrigerator is an electronic appliance using a high voltage/a highcurrent. Therefore, an electrical noise generation amount is relativelygreat. This means that the signal of mV unit output from the microphone8211 may be further vulnerable to the electrical noise.

Therefore, since the detection device PCB 83 is located close to theknock detection device 82, the noise may be remarkably reduced, and thusthe recognition rate may be enhanced.

Referring to FIGS. 30-33, a structure of the knock detection device 82will be described in detail. The knock detection device 82 is a devicewhich detects a user's knocking operation on the sub-door 50.

The knock detection device 82 may include a microphone module 821 whichdetects the knock-on signal, a holder 823 which accommodates themicrophone module 821, an elastic member 824 which presses the holder823 and the microphone module 821 toward the front panel 541 so that theholder 823 and the microphone module 821 are in close contact with thefront panel 541, and a support member 825 which supports the elasticmember 824 and the holder 823.

The microphone module 821 includes the microphone 8211 which directlysenses a sound wave, and a microphone accommodation part 8212 whichaccommodates the microphone 8211. The microphone 8211 serves to directlysense the sound wave, is formed in a circular shape having apredetermined thickness, and installed and fixed into the microphonemodule 821. One surface of the microphone 8211 may be referred to as asound wave receiving part 8213 which receives the sound wave, and thesound wave receiving part 8213 is disposed toward an opening 8214 of themicrophone accommodation part 8212. The other side of the microphone8211 may be connected to a signal line 8216, and the signal line 8216may also be connected to the detection device PCB 83.

The microphone accommodation part 8212 is formed of an elastic materialsuch as rubber, and also formed to be in close contact with the frontpanel 541. To this end, the opening 8214 may be formed at one side ofthe microphone accommodation part 8212 close to the microphone 8211installed in the microphone accommodation part 8212, and a circularprotrusion 8215 may be formed at a circumference of the opening 8214.The protrusion 8215 serves to enable the microphone accommodation part8212 not to be inclined in one direction when the microphoneaccommodation part 8212 is in close contact with the front panel 541,and also to enable an entire opened front surface of the opening part403 to be maintained in a closely contacting state with the front panel541.

A predetermined sealed space may be formed between the opening 8214 andthe sound wave receiving part 8213 which are in close contact with eachother by the protrusion 8215. Therefore, a front of the closelycontacting space is sealed by a medium, i.e., the front panel 541.Accordingly, vibration transmitted through an inside of the mediumvibrates air in the predetermined space, and the sound wave due to thevibration may be received by the microphone 8211.

Due to such a sealing process, introduction of external noise orvibration into the predetermined space may be minimized. Thus, an errorin determining a knock-on operation or a malfunction due to the externalnoise may be considerably reduced, and very accurate recognition ratemay be ensured. That is, accuracy in determining the knock-on operationwhen a knock-on input is applied may be remarkably increased.

A module seating part 8231 in which the microphone module 821 isaccommodated and which is opened toward the front panel 541 may beformed at the holder 823. The microphone module 821 may be formed sothat at least the protrusion 8215 protrudes further than a front surfaceof the holder 823 while the microphone module 821 is seated on themodule seating part 8231.

A holder slot 8232 through which the signal line connected to themicrophone 8211 passes is formed at the holder 823. The holder slot 8232is formed to be opened at one side of the module seating part 8231.

Also, a first elastic member fixing part 8233 which protrudes so thatthe elastic member 824 is installed and fixed thereto is formed at arear surface of the holder 823. The first elastic member fixing part8233 may be formed to extend and to pass through one end of the elasticmember 824 having a coil shape.

A holder coupling part 8234 which is formed in a hook shape and coupledto the support member 825 is formed at both sides of the holder 823. Dueto the holder coupling part 8234, the holder 823 is coupled so as not tobe separated by the support member 825. And also, due to the hook shapeof the holder coupling part 8234, movement of the holder 823 in adirection which is inserted into the support member 825 is notrestricted.

A front surface of the support member 825 is formed to be opened, andalso formed so that the holder 823 is inserted through the opened frontsurface thereof. And a second elastic member fixing part 8251 whichprotrudes so that the elastic member 824 is installed and fixed theretomay be formed at an inside of the holder 823. The second elastic memberfixing part 8251 may be located on an extension line of the firstelastic member fixing part 8233, and may be inserted so as to passthrough one end of the elastic member 824.

Therefore, even though the elastic member 824 is compressed to press theholder 823, the elastic member 824 may stably press the holder 823toward the front panel 541 without being buckled.

By the elastic member 824, the microphone module 821 may be maintainedin a closely contacting state with the front panel 541, andparticularly, may be always maintained in the closely contacting statewith the front panel 541 without a position change of the microphonemodule 821 due to a shock generated when the main door 40 and thesub-door 50 are closed and opened or an inertial force generated whenthe main door 40 and the sub-door 50 are rotated.

A support member slot 8252 may be formed at one side of the supportmember 825. The support member slot 8252 may be formed on an extensionline of the holder slot 8232. Therefore, the signal line passing throughthe holder slot 8232 may pass through the support member slot 8252, andmay be connected to the detection device PCB 83.

A support member fixing part 8254 is formed at the other side of thesupport member 825. The support member fixing part 8254 may be formed toextend outward, and may be installed and fixed to a detecting devicecoupling boss 5874 formed on the accommodating part case 587 by a screw.The detecting device coupling boss 5874 is formed to be exposed throughthe sensor opening 584, and enables the knock detection device 82 to beinstalled and fixed through the sensor opening 584 after the knockdetection device 82 is inserted.

The knock detection device 82 is located at the edge of the front panel541, but an effective input part for the user's knocking operation isnot limited to this configuration. In a state in which the knockdetection device 82 is in close contact with the medium, even though theknocking operation is applied to any positions, the sound wave may betransmitted through the continuous same medium due to a property of themicrophone 8211 which detects the sound wave generated by the vibration,instead of the vibration itself, and thus may be effectively detected.Therefore, a position of the knock detection device 82 may be disposedat one end at which the electric wires may be arranged and a visiblearea of the sub-door 50 may also be maximized. At the same time, eventhough the user knocks on any point of the front panel 541, the soundwave may be detected through the microphone 8211 which is in closecontact with the same medium.

Specifically, an area to which a user's knocking input is applied may bean entire area which is defined by the front surface of the front panel541. Most of the front panel 541 except a boundary portion thereof is asee-through area which selectively becomes transparent, and the knockdetection device 82 may not be disposed thereat.

Therefore, it is preferable that the knock detection device 82 islocated at the area of the bezel 5411 in the front panel 541. Inparticular, the bezel 5411 located at the upper end and left and rightsides of the front panel 541 may be minimized by locating the knockdetection device 82 at the lower end of the front panel 541 rather thanboth of the left and right sides thereof. By such a shape of the bezel5411, the see-through area may be expanded. Since the knock detectiondevice 82 is located at the lower end of the front panel 541 on which auser's eyes are relatively less focused, the wider see-through area maybe provided to the user.

Since the knock detection device 82 is located at the area of the bezel5411, is not exposed to an outside, and has a structure which is inclose contact with the front panel 541, the user's knocking operationmay be detected even through the user knocks on any position of thefront panel 541.

The front surface of the panel assembly 54 may be vibrated by the shockgenerated when the main door 40 and the sub-door 50 are opened andclosed, an external loud noise or the like, and such an input due to theexternal environments may be recognized as a knock signal.

The detection device PCB 83 may be set so that a user's operation whichknocks several times the front surface of the panel assembly 54 may berecognized as a normal knock input. More specifically, the user'soperation which knocks several times the front surface of the panelassembly 54 at predetermined time intervals may be recognized as thenormal knock input.

For example, when the user knocks twice the front surface of the panelassembly 54 within a predetermined time, it may be recognized as thenormal knock input.

The door opening assist device 588 is provided at the lower portion ofthe door liner 58. The door opening assist device 588 may include anelastic member accommodation part 5881 which is recessed inside the doorliner 58, an elastic member 5882 which is accommodated in the elasticmember accommodation part 5881, and a pressing member 5883 which issupported by the elastic member 5882.

While an external force is not applied, the pressing member 5883 issupported by the elastic member 5882, and protrudes from the door liner58, as illustrated in FIG. 33. Therefore, when the sub-door 50 isclosed, the pressing member 5883 becomes in contact with the main door40, and compresses the elastic member 5882. When the user operates theoperating button 231 of the handle 23 to open the sub-door 50 while thesub-door 50 is closed, the coupling between the locking unit 232 and therestricting member 404 is released, and the sub-door 50 is rotated andopened by an elastic force of the elastic member 5882.

As illustrated in FIGS. 34-37, the refrigerator 1 includes the maincontrol part 2 which controls the operation of the refrigerator 1, andthe main control part 2 may be connected to a door switch 21. The doorswitch 21 may be provided at the cabinet 10, and may detect opening ofthe refrigerator compartment door 20 or the main door 40, and may alsobe provided at the main door 40, and may detect opening of the sub-door50.

The main control part 2 may be connected to the door lighting unit 49,and may enable the door lighting unit 49 to be turned on when thesub-door 50 is opened or the knock-on signal is input. The main controlpart 2 may be connected to the detection device PCB 83 which isconnected to the knock detection device 82.

In a general state in which a separate operation is not applied to therefrigerator 1, the panel assembly 54 is in the opaque state like themirror surface, as illustrated in FIG. 36. In this state, it isimpossible to see through the inside of the refrigerator.

In this state, the knock detection device 82 is maintained in anactivated state in which the user may input the operation anytime[S110].

In this state, when the user performs a knock-on operation which knockson the front surface of the sub-door 50, i.e., the front panel 541 tocheck a food storing state in the refrigerator, the knock detectiondevice 82 may detect the knock-on operation, and the detection devicePCB 83 determines whether the knock-on operation is valid.

Specifically, when the user knocks on the front panel 541, the soundwave due to the vibration generated at this point is transmitted alongthe front panel 541 formed of the same medium, and the microphone 8211which is in close contact with the front panel 541 receives the soundwave.

The received sound wave is filtered and amplified while passing througha filter and an amplifier, and transmitted to the detection device PCB83. The detection device PCB 83 determines the knock with the signalwhich is collected and analyzed to detect the knock signal.

That is, in the case of the sound wave which is generated by the noiseor the shock inside or outside the refrigerator 1, there is a differencefrom the sound wave generated by the knocking operation in a propertythereof, and thus the detection device PCB 83 determines whether theuser performs the knocking operation through the signal corresponding tothe property of the knock signal.

In a specific situation, a signal similar to the knock signal may begenerated, or a shock similar to the knock may be applied to the frontpanel 541 due to the user's carelessness or inexperienced operation, orthe external noise may be recognized as a signal similar to a wavelengthof the knock signal.

When the main door 40 or the sub-door 50 is opened, the knock detectiondevice 82 may be deactivated, or may ignore the input signal, and thusthe malfunction may be prevented [S120].

Meanwhile, when the valid knock-on signal is detected, and the detectiondevice PCB 83 transmits the valid signal to the main control part 2, themain control part 2 turns on the door lighting unit 49.

When the door lighting unit 49 is turned on, the inside of the openingpart 403 becomes bright, and the light inside the refrigerator passesthrough the panel assembly 54. In particular, when the light passesthrough the front panel 541, the front panel 541 becomes transparent,and thus the inside thereof may be seen through, as illustrated in FIG.37.

When the sub-door 50 becomes transparent, the user may confirm theaccommodation space inside the main door 40 or the space inside therefrigerator, and thus may open the sub-door 50 to store the food, ormay perform a necessary operation [S130].

The turned-on door lighting unit 49 may be maintained in a turned-onstate for a preset time, e.g., 10 seconds, and thus may allow the userto sufficiently confirm an internal state of the refrigerator 1.

When the present time passes, the door lighting unit 49 is turned off[S140].

While the door lighting unit 49 is turned on, a valid knock-on operatingsignal may be input by the user before the preset time passes.

That is, when the user performs the knocking operation to confirm theinside the refrigerator 1, but a separate operation is not needed, thedoor lighting unit 49 may be turned off before the preset time passes.

For example, in a state in which the user confirms an accommodationstate inside the refrigerator 1 within 5 seconds after the door lightingunit 49 is turned on, when it is intended that the sub-door 50 becomesopaque, the knocking operation may be performed again on the frontsurface of the sub-door 50, i.e., the front panel 541.

At this point, when it is determined that the knocking operation isvalid, the door lighting unit 49 may be turned off before the presettime passes. Of course, validity determination of the knocking operationmay be set to be the same as the operation S120, and if necessary, maybe set to another knock input pattern [S150].

When the preset time passes after the door lighting unit 49 is turnedon, or the valid knock-on signal is input, the door lighting unit 49 maybe turned off.

When the door lighting unit 49 is turned off, the inside of therefrigerator 1 becomes dark, and the outside thereof is in a brightstate. In this state, the light outside the refrigerator 1 is reflectedby the front panel 541, and thus the front surface of the sub-door 50 isin a mirror-like state, and the user may not see through the insidethereof. Therefore, the sub-door 50 is maintained in the opaque stateuntil a new operation is input [S160].

What is claimed is:
 1. A refrigerator, comprising: a cabinet having astorage chamber defined therein; a door connected to the cabinet andconfigured to open and close the storage chamber, the door comprising: adoor frame having an opening; a panel assembly configured to cover theopening of the door frame, wherein the frame and the panel assemblydefines an insulation space in which an insulating material is filled;and a lighting unit to emit light such that the light passes through thepanel assembly; and a knock detector in contact with the panel assembly,and configured to detect a user knocking operation on the panelassembly; and a controller provided in the cabinet and configured toturn the lighting unit on based on the knock detector detecting soundwaves from the user knocking operation applied on the panel assembly,wherein an electric wire connects the knock detector to the controller,and wherein the electric wire extends in the insulation space along alateral side of the panel assembly toward a hinge of the door and isconnected to the controller.
 2. The refrigerator of claim 1, wherein thepanel assembly comprises: a front panel that defines a front outerappearance of the door and including a bezel provided at a perimeterthereof; an insulating panel provided at a rear side of the front panel;and a spacer provided between the front panel and the insulating panel,wherein the knock detector is in contact with the bezel.
 3. Therefrigerator of claim 2, wherein knock detector comprises a microphonethat senses sound waves, and a microphone accommodation portion thataccommodates the microphone.
 4. The refrigerator of claim 3, wherein themicrophone accommodation portion is in contact with the bezel.
 5. Therefrigerator of claim 1, wherein the door frame includes an upper hingeinstallation portion that is recessed downward, and wherein a hinge holeis provided in the upper hinge installation portion through which theelectric wire passes.
 6. The refrigerator of claim 5, wherein doorfurther comprises a hinge cover that covers the hinge installationportion and the electric wire.
 7. The refrigerator of claim 1, whereinthe door frame comprises: an outer plate; a door liner provided at arear side of the outer place; and a support frame configured to connectthe outer plate with the panel assembly.
 8. The refrigerator of claim 7,wherein the support frame is provided in the insulation space and theinsulating material covers the support frame.
 9. The refrigerator ofclaim 7, wherein the panel assembly comprises: a front panel thatdefines a front outer appearance of the door, a spacer provided betweenthe front panel and the insulating panel; and an insulating panelprovided at a rear side of the front panel, wherein the support framecomprises: a first support that faces a rear surface of the front panel,and a second support that faces a rear surface of the outer plate. 10.The refrigerator of claim 9, wherein the first support is in contactwith the rear surface of the front panel, and the second support is incontact with the rear surface of the outer plate.
 11. The refrigeratorof claim 9, wherein the outer plate comprises a bent portion that isbent toward the door liner, and wherein the support frame comprises aninsertion portion configured to receive the bent portion.
 12. Therefrigerator of claim 11, wherein the insertion portion is providedbetween the first support and the second support.
 13. The refrigeratorof claim 11, wherein the first support is provided between the bentportion and the spacer.
 14. The refrigerator of claim 11, wherein aprojection is formed on the support frame, and wherein a hole is formedon the bent portion of the outer plate, into which the projection of thesupport frame of the door is inserted.
 15. The refrigerator of claim 9,wherein the first support of the support frame is positioned closer toan interior of the storage chamber than a rear surface of the outerplate of the door.
 16. The refrigerator of claim 9, further comprising aheater received in the first support of the support frame.
 17. Arefrigerator, comprising: a cabinet having a storage chamber definedtherein; a door connected to the cabinet and configured to open andclose the storage chamber, the door comprising: a door frame having anopening; a panel assembly configured to cover the opening of the doorframe, wherein the frame and the panel assembly defines an insulationspace in which an insulating material is filled; and a lighting unit toemit light such that the light passes through the panel assembly; and aknock detector in contact with the panel assembly, and configured todetect a user knocking operation on the panel assembly; and a controllerprovided in the cabinet and configured to turn the lighting unit onbased on the knock detector detecting sound waves from the user knockingoperation applied on the panel assembly, wherein an electric wireextends through the insulation space and though a hinge of the door tooutside of the door to connect the knock detector to the controller. 18.The refrigerator of claim 17, wherein the door frame includes an upperhinge installation portion that is recessed downward, and wherein ahinge hole is provided in the upper hinge installation portion throughwhich the electric wire passes.
 19. The refrigerator of claim 18,wherein door further comprises a hinge cover that covers the hingeinstallation portion and the electric wire.
 20. The refrigerator ofclaim 17, wherein knock detector comprises a microphone that sensessound waves, and a microphone accommodation portion that accommodatesthe microphone.